As a cold front moved through the region, widespread showers and storms developed. Some of the storms produced damaging winds, large hail, and flash flooding.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS LSX wrote it up.
As a cold front moved through the region, widespread showers and storms developed. Some of the storms produced damaging winds, large hail, and flash flooding.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS St. Louis, MO wrote its last area forecast discussion before the first event at May 28, 11:57 AM CST, 1 hour 33 minutes earlier.
Area Forecast Discussion...Updated Aviation National Weather Service Saint Louis MO 1257 PM CDT Thu May 28 2020 .SHORT TERM... (Through Late Friday Afternoon) Issued at 339 AM CDT Thu May 28 2020 There are a couple of items to note first thing this morning. The first has to deal with fog potential, largely concerning sections of central Missouri. Surface analysis continues to reflect a stationary boundary that stretches north to south through interior sections of the state. Consequently, weak moisture convergence resides along this area with calm/light winds and low dewpoint depressions. Fog has become locally dense in some sections of the state, but has largely been lighter/more transient over Jefferson City and Columbia. Therefore, we continue to monitor any trends and held off on any headlines for now. The second item continues to be the closed upper low that has plagued the region with shower and thunderstorm activity over the last few days. It has not made much progress over the last 12 hours. Water vapor imagery shows the system continuing to rotate near the Oklahoma/Arkansas border this morning with scatter showers and a few embedded thunderstorms rotating around it. A few of these storms have produced hail west of Poplar Bluff overnight, rapidly weakening with northward movement. While a couple of thunderstorms are possible, much of the activity should remain in the form of showers through the mid-morning hours. As we head into the afternoon, there is some hint that clouds may break to allow an occasional peek of sunshine. This will run well ahead of a cold front and well within a moisture rich and unstable air mass. While the NAM is very aggressive with instability (2000+ J/Kg), the HREF SBCAPE probabilities lean toward more realistic values of 1000-1500 J/kg over a broad area. This is expected to lead to scattered showers and thunderstorms through the early afternoon and evening. Given weak shear and high PWATs pushing 1.5 in., much of the impact will be related to general thunderstorm threat and locally heavy rain. Meanwhile, forcing along the cold front will ignite showers and thunderstorms from Kansas City though north-central Missouri. The upper low begins to open and finally makes northeast progress overnight. The front shifts southeast late this evening and overnight. Storms along the front will likely weaken with showers pushing into far southeast Missouri and the eastern sections of the forecast area. Expect showers to move east around mid-morning Friday with moist air being replace by lower dewpoints, comfortable temperatures in the 70s and ample sunshine. Maples .LONG TERM... (Friday Night through Wednesday) Issued at 339 AM CDT Thu May 28 2020 Ensemble means and deterministic solutions continue to point to a dry and pleasant start to the period. A strengthening surface high near the Canadian border will build south and elongate underneath the eastern periphery of a longwave ridge to the west. The pattern doesn't change too much between Saturday and Sunday, resulting in low dewpoints with high temperatures in the low to mid-70s. As mentioned in the prior update, there is a caveat to the otherwise exceptional weekend. Guidance continues to show the potential for upper level shortwave energy tracking around the northern periphery of the upper ridge. This could lead to thunderstorm potential over the plains, some of which could make it into northwest Missouri late Saturday into Sunday. This will continue to be something to watch for late Saturday into Sunday with just slight chances for showers and weakening thunderstorms introduced to the northwest CWA Saturday night. Ensemble spread is fairly thin even into next week with some small, but notable differences in the GFS/ECM. The upper ridge axis continues to lean eastward into the plains from Monday through Wednesday, pushing the general storm track to the north. Surface high pressure becomes positioned into the Ohio Valley with south and southwesterly surface flow taking over through the region. The ECM favors a stronger and broader longwave upper ridge, as the GFS seems to be slightly less so (593 vs 590, respectively). Either of the solutions would validate warming MOS trends with temperatures going from well into the 70s Monday to the upper 80s to near 90 Tuesday and Wednesday. Current forecast temps may be a touch too cool for this two day stretch, pending any high cloud potential from thunderstorm activity which should largely stay north. Maples && .AVIATION... (For the 18z TAFs through 18z Friday Afternoon) Issued at 1242 PM CDT Thu May 28 2020 Scattered thunderstorms have developed across eastern Missouri and parts of southwest IL, and the metro St. Louis terminals will have the biggest potential for thunder impacts this afternoon. Currently the size of individual storms is small so pinning down a time they will impact a terminal is difficult and have opted for either VCTS or a short TEMPO group for now. Showers will be the more dominant precipitation impacting KCOU and KUIN this afternoon and evening with a lesser threat of thunderstorms, however MVFR flight conditions should largely dominate at these locations. Overall the thunder threat should diminish after 01-02z. A band of stratus with an advancing cold front will move into eastern MO and west central IL near 05z and then should depart by 11z or so. Northwest winds gusting up to 20 kts will dominate on Friday with VFR flight conditions. SPECIFICS FOR KSTL: Scattered thunderstorms have developed across eastern Missouri, and gauging the direct impact to KSTL is difficult to pin down given their small size until they congeal. I have opted for VCTS for now and will amend accordingly. Overall the thunder threat should diminish after 01-02z with showers at times this evening. A band of stratus associated with an advancing cold front will move into the terminal near 05z bringing MVFR flight conditions, and then should depart by 11z or so. Northwest winds gusting up to 20 kts will dominate on Friday with VFR flight conditions. Glass && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && WFO LSX
Hazardous Weather Outlook National Weather Service Saint Louis MO 418 AM CDT Thu May 28 2020 ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027- 034>036-041-042-047>052-059>065-072>075-084-085-099-290930- Adams IL-Audrain MO-Bond IL-Boone MO-Brown IL-Calhoun IL-Callaway MO- Clinton IL-Cole MO-Crawford MO-Fayette IL-Franklin MO-Gasconade MO- Greene IL-Iron MO-Jefferson MO-Jersey IL-Knox MO-Lewis MO-Lincoln MO- Macoupin IL-Madison IL-Madison MO-Marion IL-Marion MO-Moniteau MO- Monroe IL-Monroe MO-Montgomery IL-Montgomery MO-Osage MO-Pike IL- Pike MO-Ralls MO-Randolph IL-Reynolds MO-Saint Charles MO- Saint Clair IL-Saint Francois MO-Saint Louis City MO-Saint Louis MO- Sainte Genevieve MO-Shelby MO-Warren MO-Washington IL-Washington MO- 418 AM CDT Thu May 28 2020 This Hazardous Weather Outlook is for portions of eastern and central Missouri as well as west central and southwest Illinois. .DAY ONE...Today and tonight. There is chance for thunderstorms today with thunderstorms more likely this afternoon into tonight. Major flooding is occurring or forecast along the Illinois River above Hardin. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. There is a slight chance for thunderstorms over portions of northeast Missouri Saturday night and sections of northeast Missouri and west-central Illinois again Sunday night. There is a slight chance for thunderstorms over much of the area late Wednesday. Major flooding is occurring or forecast along the Illinois River above Hardin. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated through tonight. Maples
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
1009 AM CDT THU MAY 28 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0734 PM TORNADO 2 WSW POSEY 38.52N 89.39W
05/27/2020 CLINTON IL PUBLIC
SHORT-LIVED TORNADO OBSERVED BY SEVERAL
INDIVIDUALS AT A DISTANCE. TIME AND LOCATION
ESTIMATED FROM REPORTS AND RADAR.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
150 PM CDT THU MAY 28 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0903 AM HEAVY RAIN 2 NE GRANITE CITY 38.73N 90.10W
05/28/2020 M1.08 INCH MADISON IL PUBLIC
&&
TESThe St Louis radar (KLSX), 65 km away, was scanning. The volume nearest the first event began at 19:30 UTC.
1 flash flood, 1 hail. Local standard time, as filed.
Up to 3 inches of rain fell in about an hour and a half causing flash flooding. Several secondary roads near Olney were flooded.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Missouri in 2020Every state in 2020This day in weather historyWarnings in Missouri, May 2020
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 887464, 887463.